The present invention relates to manual control devices having a joystick. Such devices are used in the field of industrial control technology to control construction machines or industrial robots. The two-dimensional motions of the control stick (joystick) are is, converted here, via contacts or relays, into electrical signals, which are transmitted especially in wireless fashion by means of a remote-control transmitter to a receiver in or on the industrial equipment to be controlled, where they bring about a corresponding motion, such as deflection of a robot arm.
For the pivoting motion, the joystick must be retained in a joint that is sturdy, invulnerable to dirt, and sealed against splashing water and that has great stability under load, so that it can function reliably under the often rough conditions of use in the industrial control field.
A known manual control device is disclosed in EP 0 683 906 B1. The joint of this device is an elastomer joint, whose cross-sectional design is such that upon maximal deflection of the joystick, an essentially rectilinear surface line of intersection is created in the region of greatest expansion, while the opposed region, stressed for compression, becomes increasingly deeper. This arrangement makes good retention of a fixed articulation point possible even in the pivoted position of the joystick, but the relatively voluminous design of the elastomer joint leads to large-volume compression or stretching of the various regions when they are stressed during pivoting, which with frequent stress causes fatigue of the elastomer joint.
The present invention provides a refinement of the previously known elastomer joint such that greater reliability and a greater stability under load are achieved.
The invention provides a manual control device composed of: a housing; a joystick; and a joint supporting the joystick in the housing to enable the joystick to pivot about two mutually orthogonal axes relative to the housing. The joint is an elastic molded plastic part composed of an interior portion secured to the joystick, a peripheral portion secured to the housing and a connecting portion extending between, and connecting, the interior portion and the peripheral portion. The interior portion has the form of a first cylinder and the peripheral portion has the form of a second cylinder, the first and second cylinders being concentric with one another when the joystick is in a neutral position. The connecting portion has a frustoconical shape when the joystick is in the neutral position and is stressed when the joystick is pivoted away from the neutral position.
The fundamental concept of the invention is that because the connecting region that is stressed upon pivoting is designed with relatively narrow walls in the form of a frustoconical jacket, more-precisely defined stress regions are created. These regions are defined predominantly as walls stressed for expansion on the one hand and as jointlike, relatively small-volume compression regions on the other hand.
The demands made can be met in conjunction with a suitable choice of the opening angle of the frustoconical connecting region, of the material comprising the joint, and of the wall thickness of the connecting region.